In acidic medium, `H_(2)O_(2)` changes `Cr_(2)O_(7)^(2-)` to `CrO_(5)` which has two (-O-O-) bonds. Oxidation state of Cr in `CrO_(5)` is

Options

A. `+5`
B. `+3`
C. `+6`
D. `-10`

Answer

To find the oxidation state of chromium in CrO5, we can follow these steps:

### Step 1: Write the chemical formula and identify the components
The compound in question is CrO5. This compound contains one chromium (Cr) atom and five oxygen (O) atoms.

### Step 2: Assign oxidation states to oxygen
In most compounds, oxygen has an oxidation state of -2. Since there are five oxygen atoms in CrO5, the total contribution of oxygen to the oxidation state is:
\[ 5 \times (-2) = -10 \]

### Step 3: Set up the equation for the oxidation state of chromium
Let the oxidation state of chromium be \( x \). The overall charge of the compound is neutral (0), so we can set up the equation:
\[ x + (-10) = 0 \]

### Step 4: Solve for the oxidation state of chromium
Rearranging the equation gives:
\[ x - 10 = 0 \]
\[ x = +10 \]

### Step 5: Adjust for the structure of CrO5
However, we need to consider the structure of CrO5, which includes peroxide linkages. In CrO5, there are two -O-O- (peroxide) bonds. Each peroxide bond contributes an additional -1 oxidation state for each oxygen involved in the bond.

Thus, for the two peroxide linkages (which involve 4 oxygen atoms), we need to adjust the oxidation state:
- Each of the 4 oxygen atoms in the peroxide linkages contributes -1 (instead of -2).
- The remaining oxygen atom contributes -2.

### Step 6: Recalculate the total contribution of oxygen
The total contribution from the 4 peroxide oxygen atoms is:
\[ 4 \times (-1) = -4 \]
And from the remaining oxygen atom:
\[ -2 \]
So the total contribution from all oxygen atoms is:
\[ -4 + (-2) = -6 \]

### Step 7: Set up the final equation for chromium
Now we can set up the equation again:
\[ x + (-6) = 0 \]
\[ x = +6 \]

### Conclusion
The oxidation state of chromium in CrO5 is +6.

### Final Answer
The oxidation state of Cr in CrO5 is +6.

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